Recovery of organic liquids which are soluble or partially soluble in water



3 Sheets-Sheet 1 W. E. EDWARDS Filed June 25, 1941 OR PARTIALLY SOLUBLE IN WATER RECOVERY OF ORGANIC LIQUIDS WHICH ARE SOLUBLE \I' Ll-l-l. IIIIIIIII. I llhl Jan. 18, 19,44.

Inventor M g wm.

Attorney Jan. 18, 1944. w. E. EDWARDS 2,339,386

RECOVERY OF ORGANIC LIQUIDS WHICH ARE SOLUBLE 0R PARTIALLY SOLUBLE IN WATER Filed June 2S, 1941- 3 Sheets-Sheet 2 Fig.2;

I rwentar Attorney- Jan- 18, w E EDWARDS. v

RECOVERY OF ORGA NIC LIQUIDS WHICH ARE SOLUBLE OR PARTIALLY SOLUBLE IN WATER Fild June 23, 1941 3 Sheets-Sheet 3 A ttorrwy- Patented a... 18,1944

2,339,386. FlCE RECOVERY OF ORGANIC LIQUIDS WHICH ARE SOLUBLE OR IN WATER PARTIALLY SOLUBLE William Ernest Edwards, Leigh, England, assignor to Sutcliile, Speakman and Company Limited, Leigh, England Application June 23, 1941, Serial No. 399,426

' In Great Britain September 7, 1939 3 Claims. The invention relates to the recovery from aqueous solution of organic liquids such as ethyl acetate. v

In the recovery of organic liquids such as an organic solvent from air laden with the solvent it is usual to pass the solvent laden air through a sorptive medium such as activated carbon from which the solvent is recovered on its being flushed with steam in known manner. Where however the organic solvent is wholly or partly soluble in water a considerable part becomes admixed with the aqueous condensate and it is necessary to recover that part by'redistillation and the use of a special plant for the purpose.

The invention has among its objects to avoid this disadvantage.

According to the invention organic liquids in aqueous solution are passed downwardly through a sorptive medium such as activatedcarbon in the charging phase, and steam then passed in the flushing phase upwardly into contact with the active carbon whereby the active carbon is heated to the temperature at which the organic liquid is vaporised, the steam condensed in heating the active carbon is drained away and the further steaming serves to drive the organic liquids out of the active carbon substantially free of Water.

An apparatus for eflecting the recovery of organic liquids by the method described may comprise a container for the sorptive medium, an in- At the upper end the container has connected to it an inlet pipe II. for the admission of the aqueous solution of the solvent under control by the valve l3. The inlet pipe I! is connected to let pipe for aqueous solution and an outlet pipe for the vapour of the organic liquid connected to the upper part of the container and an outlet pipe for the water freed of the organic liquid, an inlet pipe for steam and a trap device for condensed steam connected to the lower part of the container and valves or other means for controlling the charging and flushing operations in the container.

The invention is illustrated by way of example in the accompanying drawings in'which:

Figure 1 is a diagram of apparatus according to the invention.

Figures 2, 3 and 4 are respectively end eleva tion, plan and front elevation of another apparatus constructed according to the invention, in

which a pair of adsorption filters is employed operating on ilternating phases.

In carrying the invention into effect in the recovery of a solvent such for example. as ethyl acetate from an aqueous solution, the apparatus as diagrammatically illustrated inFigure 1 comprises a substantially'cylindrical container ID for the sorptive vmedium II, which advantageously may be active carbon in the condition'of grains. The container serves as -an adsorption filter for the recovery of solvents.

the lower end of a vapour outlet pipe M beneath the controlling valve l5, which is closed during the charging phase. The outlet pipe I serves in the flushing phase to convey the separated vapour to a condenser IS, the latter in tm'n communicating with a recevier or storage-tank l1, into which the recovered condensate passes through the outlet pipe l8.

An outlet pipe I9 at the lower end of the container has three'branches, 2|, 22 and 23,-which are controlled respectively by valves 2!, 25 and 26. The branch 2| serves as the outlet for the water from which the solvent has been separated by adsorption in the charging phase, the branch 22 serves as an inlet pipe for the hot steam used in the steaming or flushing phase, while the branch 23 extends downwardly and is connected with a tank 21, the outlet from which maybe float-controlled for the release 01' the condensed water recovered in the flushing phase. The

branch 2| may advantageously extend upward and be provided in position above the container with an outlet 28 for the water freed from the solvent, thus ensuring that the container 10 is maintained full of the aqueous solution'during the charging phase. In operation the aqueous solution of the solven is passed downwardly from the inlet pipe l2 through the sorptive medium Ii during the charging phase, whereby the solvent is adsorbed and the water freed of the solvent passes through the branch 21 and is discharged by way of the outlet 28 as indicated in dot and dash lines, the valves 25, 28 and I5 being closed. I

When the sorptive medium H is nearing saturation point the valve ii on the inlet pipe l2 and the valve 24 on the outlet branch 2| are closed and the valves l5 and 25 on the pipes I 4 and 22 respectively are opened, for the admission into the container of hot'steam for the flushin operation. The steam as indicated in dotted lines passes through the pipes 22 and I8 upwardly through the sorptive medium ll charged with the condenser l6 and the condensate passing from the condenser it through 'the pipe l8 to the receiver ll.

a will be understood that the steam I upwardthroughthe sorptive medium in the 4 flushing phase causes the heating of the sorptive medium and that the condensed steam, free of the*solvent, drains downward into the tank 21 by way of the pipes "and I I. The sorptive medicated by a thermometer 29 set in the outlet pipe Thus, the solvent is distilled from the sorptive medium in an upward direction, the wet carbon serving as a fractionaton or dephlegmator by which practically pure vapour of the solvent passes through to the condenser while the aqueous condensate runs back through the sorptive medium to drain into the receiving tank.

In carrying the invention into eflect as -illusplant (not shown) is passed for preliminary separation to a separator 3|. The inlet pipe supplying the containers 30, 60. receives the aqueous solution from the separator 3|, the flow of the solution being measured by a meter 33. Near the containers the'pipe 33 is diverted to supply the container 30 while a branch 32 is provided to supply the container 50, the admission of the aqueous solution to the two containers being controlled respectively by the valves 34 and 84 and being effected by way of the respective vapour outlet pipes 35 and G5. The outlet pipes 33, 56 branch rearwardly at 31 and 31 and forwardly at 38 and 58 respectively. The branches 3'! and 81 are respectively connected by Pipes 33, 53 to a common two-way controlling valve 40 from which there extends upwardly a common vent pipe 4| from which the water outlet pipe 42 branches near the top of the containers. The branches 38 and 88 are similarly" connected by pipes 43, 13 to a two-way controlling valve 44 having an outlet leading to the float tank 45. The vapour outlet pipes 35, 55 are controlled respectively by the valves 46 and 18 which are connected by a pipe 41 having a pipe 48 connect ing it with the condenser 49 through which cooling water is passed from 58 to The condensate passes by way of the pipe 52 into a receiver or separator 53 where separation is effected by gravity and whence the separated solvent free of water passes away by an overflow pipe 54 opening into the upper end of the receiver or separator 53 while the separated water is drawn from the bottom of the separator 53 byway of the downwardly depending pipe and the outlet fitting ethyl acetate that the aqueous solution of the solvent contains, only from 3 to 5%. This in normal practice is either lost or requires distillation in which latter case the whole of the liquor has to be heated for reclaiming the ethyl acetate, whereas according to the invention the ethyl acetate is concentrated in the carbon that is to say to between %.to of the weight of the car- 45 and 51' closed while the valve 48 is set to conmeet the pipe 39 to the vent pipe 4| and the valve It is found in actual practice with respeotto,

bon. Thus, the method of the invention presents advantages of considerabl practical importance. Furthermore, the amount of hot steam required in the flushin phase is very small and practically the whole of the solvent is recovered.

It will be understood that the distillation of the ethyl acetate from the carbon is complete when the temperature of the vapour issuing from the adsorptive filter begins suddenly to rise that is to say when the-lower boiling solvent vapours have passed off and the steam alone commences to pass through.

In the construction illustrated in Figures 2 to 4 a separator 53 is provided under the condenser for the purpose of separating any aqueous con-' densate which comes away from the carbon when the ethyl'acetate has been completely distilled oil. The aqueous condensate' is returned for passage through one of the containers during the charging phase, as hereinbefore described.

It will be understood that the invention is of general application for the recovery of vapours that are soluble or partially soluble in water such as low boiling hydrocarbons or other substances such as benzene and-butyl acetate or amyl acetate, the temperature conditions in the flushing phase being determined according to the boiling point of the materiaL.

By the process of' the invention the'organic liquids are recovered directly from the active carsteam condensed in heating the sorptive medium,

continuing the steaming to drive from the heated sorptive medium the vaporised organic liquid substantially free of water and condensing the vapour to recover the organic liquid.

2. An apparatus for carrying out the method of claim 1, comprising a container for the sorptive medium, an inlet pipe for aqueous solution and an outlet pipe for the vapour of the organic liquid connected to the upper part of the container above the sorptive medium and an outlet pipe for the water freed of theorganic liquid, an inlet pipe for steam and a trap device for condensed steam connected to the lower part of the container beneath the sorptive medium and means for controlling the charging and flushing operations in the container.

3. A method of recovering organic liquids of low boiling point from aqueous solutions in which they aresoluble according to claim 1, consisting in continuing the steaming of the sorptive medium until the temperature of the discharge vapours at the vapour outlet of the container begins to rise, indicating the presence of steam.

WILLIAM ERNEST EDWARDS. 

